In recent years, some outer parts of automotive vehicles have been changed from metal members to plastic members for the purpose of vehicle body weight reduction and design flexibility improvement. In general, the plastic members are given coating.
For example, fenders and back-door panels are formed of rigid plastic materials such as sheet molding compounds (SMC) and polymer alloys. These rigid plastic members are each coated with an undercoat and a top coat, as in the case of metal materials, after coated with a primer coat. On the other hand, bumpers and side sill spoilers where bending resistance and impact resistance are required are formed of soft plastic materials such as polypropylene and urethane. These soft plastic members are each coated with a primer coat and a soft top coat.
There has also recently been proposed a coating material using a polyrotaxane known as a ring-slide gel for improvements in abrasion resistance (see Patent Document 1).    Patent Document 1: Japanese Patent Publication No. 2007-99989